Comment in:
The 1993 epidemic of pertussis in Cincinnati. Resurgence of
disease in a highly immunized population of children.
Christie CD, Marx ML, Marchant CD, Reising SF.
Department of Pediatrics, University of Cincinnati College of Medicine, OH.
BACKGROUND. In 1993 there was a resurgence of pertussis in the United States.
Altogether, 6335 cases were reported, the most in 26 years. METHODS. Using
active microbiologic surveillance, we investigated the epidemic of pertussis in
Greater Cincinnati in 1993. The population of 1.7 million in this area is served
by a single children's hospital and pertussis laboratory. We prospectively
followed patients given a new diagnosis of pertussis in July through September
1993 to determine the characteristics of the epidemic. RESULTS. From 1979 to
1992, there was a cumulative total of 542 cases of pertussis. In 1993, 352 cases
were diagnosed, an increase of 259 percent over the 1992 total. Sixty-three
percent of the cases had positive cultures for Bordetella pertussis, 18 percent
were positive on direct fluorescent-antibody testing only, and 19 percent were
diagnosed clinically. The outbreak began in the suburbs during the summer and
spread through Greater Cincinnati. Of 255 total cases diagnosed in July through
September (195 excess cases over the maximal base-line level of 20 per month in
the previous 14 years), 75 percent were in white patients and 67 percent of the
patients had private insurance or paid for care out of pocket. In 1993, as
compared with 1979 through 1992, there was a shift in incidence from younger
infants to older children; the percentages of cases according to age group were
as follows: 0 to 6 months, 53 percent from 1979 through 1992 and 35 percent in
1993 (P < 0.001); 7 months to 5 years, 33 percent and 43 percent (P < 0.002); 6
to 12 years, 5 percent and 11 percent (P < 0.001); and more than 12 years, 5
percent and 11 percent (P < 0.003). Immunization records revealed that 74
percent (75 of 101) of the children with pertussis who were 19 months to 12
years old had received four or five doses of the combined
diphtheria-pertussis-tetanus (DPT) vaccine, and that 82 percent (103 of 126) of
those 7 to 71 months old had received at least three doses of DPT vaccine. The
whole-cell vaccines used came from both of the major manufacturers (Connaught
Laboratories and Lederle Laboratories). Disease was not severe, but 80 of the
255 children (31 percent) given diagnoses during the three epidemic months were
hospitalized. There were no deaths. CONCLUSIONS. Since the 1993 pertussis
epidemic in Cincinnati occurred primarily among children who had been
appropriately immunized, it is clear that the whole-cell pertussis vaccine
failed to give full protection against the disease.
PMID: 8202096 [PubMed - indexed for MEDLINE]